David Sloan Wilson (one of the editors and authors in the JEBO special issue above) has an article in aeon magazine critiquing economics from an evolutionary angle.

Also in aeon magazine, an interesting take on obesity (HT: John Hawks). It’s fair to say that a simple “calorie in-calorie out” analysis doesn’t cut the mustard anymore. (But I don’t buy the bit about lab animal food staying the same).

2 thoughts on “A week of links”

Hi Jason,
Thanks for writing such a great blog. Just one thought: it seems to be that a key piece of evidence that nature selected for quality over quantity in the Malthusian era was that twins were (and are) very rare compared with other animals. The same can be said about the relative difficulty (compared with other animals, perhaps excluding pandas) of getting pregnant in general. Evolution really didn’t want humans to have too many children too quickly. Question: The prevalence of twins has increased over the past few decades. Is there any evidence that this has been partly due to selective pressures, rather than the more obvious explanation: fertility drugs? If so, this would support your model that suggests that the quantity genome should increase in frequency relative to the quality genome.
Peter

Two other explanations for the increase are racial differences in twin birth frequency and the increasing age of mothers (which increases twin frequency independent of fertility treatment).

I’m not aware of any published evidence of selective pressures pushing us towards having more twins, but the rarity of twin births – as you suggest – points towards past constraints on number of children. Those constraints have been substantially loosened now (along with the health risks of multiple births), so you would expect positive selection for multiple births. However, it would be a tough task to disentangle the various factors behind it.

In another paper I’ve argued that there is now positive selection for any trait that increases fertility in developed countries, so we would expect fertility to go up.